Premium
An analysis of the lamellar structure of sea urchin egg cortical granules using X‐ray scattering
Author(s) -
Whalley T.,
Grossmann J.G.,
Wess T.J.
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(00)02068-8
Subject(s) - lamellar structure , sea urchin , strongylocentrotus purpuratus , lamellar granule , vesicle , biophysics , crystallography , exocytosis , membrane , morphology (biology) , electron microscope , chemistry , biology , ultrastructure , anatomy , microbiology and biotechnology , biochemistry , optics , paleontology , physics
Cortical granules (CGs) are secretory vesicles associated with egg and oocyte plasma membranes that undergo exocytosis at fertilisation. In the sea urchin Strongylocentrotus purpuratus , the internal organisation of these CGs exhibits a lamellar‐type morphology. The different lamellar layers correspond to proteoglycans, structural proteins and enzymes required for fertilisation envelope assembly and modification of the post‐fertilisation egg surface. We have studied the lamellar structure of CGs using X‐ray scattering and reveal the contrast density variation of the lamellae in the native state. The structure of functionally competent CGs in situ differs significantly from that determined by electron microscopic studies. We observed a strong periodicity of the lamellar structure of 280 Å as opposed to the 590 Å repeat observed previously. Fusion of the CGs produced a loss of the lamellar repeat and the development of a broad peak corresponding to a 20 Å periodicity that may be indicative of the molecular packing in the resulting hydrated gel structure.